gcse.c (delete_null_pointer_checks_1): Inform caller if any null pointer checks were eliminated.

        * gcse.c (delete_null_pointer_checks_1): Inform caller if any
        null pointer checks were eliminated.  Update prototype.
        (delete_null_pointer_checks): Similarly.
        * rtl.h (delete_null_pointer_checks): Update prototype.
        * toplev.c (rest_of_compilation): Only run cleanup_cfg if
        delete_null_pointer_checks deletes one or more null
        pointer checks.  Do not run cleanup_cfg before gcse, the
        CFG is accurate and optimized at that point..

From-SVN: r54617

gcc/ChangeLog

 2002-06-13  Jeffrey Law  <law@redhat.com>
 
+	* gcse.c (delete_null_pointer_checks_1): Inform caller if any
+	null pointer checks were eliminated.  Update prototype.
+	(delete_null_pointer_checks): Similarly.
+	* rtl.h (delete_null_pointer_checks): Update prototype.
+	* toplev.c (rest_of_compilation): Only run cleanup_cfg if
+	delete_null_pointer_checks deletes one or more null
+	pointer checks.  Do not run cleanup_cfg before gcse, the
+	CFG is accurate and optimized at that point..
+
 	* rs6000.c (rs6000_frame_related): Avoid unwanted sharing
 	of hard registers.
 

gcc/gcse.c

@@ -658,7 +658,7 @@ static int handle_avail_expr	PARAMS ((rtx, struct expr *));
 static int classic_gcse		PARAMS ((void));
 static int one_classic_gcse_pass PARAMS ((int));
 static void invalidate_nonnull_info PARAMS ((rtx, rtx, void *));
-static void delete_null_pointer_checks_1 PARAMS ((unsigned int *,
+static int delete_null_pointer_checks_1 PARAMS ((unsigned int *,
 						  sbitmap *, sbitmap *,
 						  struct null_pointer_info *));
 static rtx process_insert_insn	PARAMS ((struct expr *));
@@ -5473,7 +5473,7 @@ invalidate_nonnull_info (x, setter, data)
    NPI.  NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
    they are not our responsibility to free.  */
 
-static void
+static int
 delete_null_pointer_checks_1 (block_reg, nonnull_avin,
 			      nonnull_avout, npi)
      unsigned int *block_reg;
@@ -5484,6 +5484,7 @@ delete_null_pointer_checks_1 (block_reg, nonnull_avin,
   basic_block bb, current_block;
   sbitmap *nonnull_local = npi->nonnull_local;
   sbitmap *nonnull_killed = npi->nonnull_killed;
+  int something_changed = 0;
 
   /* Compute local properties, nonnull and killed.  A register will have
      the nonnull property if at the end of the current block its value is
@@ -5605,6 +5606,7 @@ delete_null_pointer_checks_1 (block_reg, nonnull_avin,
 	  emit_barrier_after (new_jump);
 	}
 
+      something_changed = 1;
       delete_insn (last_insn);
       if (compare_and_branch == 2)
 	delete_insn (earliest);
@@ -5615,6 +5617,8 @@ delete_null_pointer_checks_1 (block_reg, nonnull_avin,
 	 block.)  */
       block_reg[bb->index] = 0;
     }
+
+  return something_changed;
 }
 
 /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
@@ -5641,7 +5645,7 @@ delete_null_pointer_checks_1 (block_reg, nonnull_avin,
 
    This could probably be integrated with global cprop with a little work.  */
 
-void
+int
 delete_null_pointer_checks (f)
      rtx f ATTRIBUTE_UNUSED;
 {
@@ -5652,10 +5656,11 @@ delete_null_pointer_checks (f)
   int regs_per_pass;
   int max_reg;
   struct null_pointer_info npi;
+  int something_changed = 0;
 
   /* If we have only a single block, then there's nothing to do.  */
   if (n_basic_blocks <= 1)
-    return;
+    return 0;
 
   /* Trying to perform global optimizations on flow graphs which have
      a high connectivity will take a long time and is unlikely to be
@@ -5666,7 +5671,7 @@ delete_null_pointer_checks (f)
      a couple switch statements.  So we require a relatively large number
      of basic blocks and the ratio of edges to blocks to be high.  */
   if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
-    return;
+    return 0;
 
   /* We need four bitmaps, each with a bit for each register in each
      basic block.  */
@@ -5719,8 +5724,10 @@ delete_null_pointer_checks (f)
     {
       npi.min_reg = reg;
       npi.max_reg = MIN (reg + regs_per_pass, max_reg);
-      delete_null_pointer_checks_1 (block_reg, nonnull_avin,
-				    nonnull_avout, &npi);
+      something_changed |= delete_null_pointer_checks_1 (block_reg,
+							 nonnull_avin,
+							 nonnull_avout,
+							 &npi);
     }
 
   /* Free the table of registers compared at the end of every block.  */
@@ -5731,6 +5738,8 @@ delete_null_pointer_checks (f)
   sbitmap_vector_free (npi.nonnull_killed);
   sbitmap_vector_free (nonnull_avin);
   sbitmap_vector_free (nonnull_avout);
+
+  return something_changed;
 }
 
 /* Code Hoisting variables and subroutines.  */

gcc/rtl.h

@@ -2035,7 +2035,7 @@ extern void reg_scan			PARAMS ((rtx, unsigned int, int));
 extern void reg_scan_update		PARAMS ((rtx, rtx, unsigned int));
 extern void fix_register		PARAMS ((const char *, int, int));
 
-extern void delete_null_pointer_checks	PARAMS ((rtx));
+extern int delete_null_pointer_checks	PARAMS ((rtx));
 
 /* In regmove.c */
 #ifdef BUFSIZ

gcc/toplev.c

@@ -2729,9 +2729,9 @@ rest_of_compilation (decl)
       if (rtl_dump_file)
 	dump_flow_info (rtl_dump_file);
 
-      delete_null_pointer_checks (insns);
-
+      if (delete_null_pointer_checks (insns))
         cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_PRE_LOOP);
+
       close_dump_file (DFI_null, print_rtl_with_bb, insns);
     }
 
@@ -2775,13 +2775,13 @@ rest_of_compilation (decl)
       if (tem || optimize > 1)
 	cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_PRE_LOOP);
       /* Try to identify useless null pointer tests and delete them.  */
-      if (flag_delete_null_pointer_checks || flag_thread_jumps)
+      if (flag_delete_null_pointer_checks)
 	{
 	  timevar_push (TV_JUMP);
 
 	  if (flag_delete_null_pointer_checks)
-	    delete_null_pointer_checks (insns);
-	  /* CFG is no longer maintained up-to-date.  */
+	    if (delete_null_pointer_checks (insns))
+	      cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_PRE_LOOP);
 	  timevar_pop (TV_JUMP);
 	}
 
@@ -2814,7 +2814,6 @@ rest_of_compilation (decl)
       timevar_push (TV_GCSE);
       open_dump_file (DFI_gcse, decl);
 
-      cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_PRE_LOOP);
       tem = gcse_main (insns, rtl_dump_file);
       rebuild_jump_labels (insns);
       delete_trivially_dead_insns (insns, max_reg_num ());